Metal chelate compounds and inks

ABSTRACT

A metal chelate compound of the Formula (1) and salts thereof:  
                 
wherein: one of A and B is OH and the other is an azotriazole group; and M is a metal or boron; and n is 0 to 4; compositions and inks containing a compound of Formula (1), a process for ink jet printing using the inks and to an ink jet printer cartridge containing the ink.

This invention relates to dyes, to inks and to their use in ink jetprinting (“IJP”). IJP is a non-impact printing technique in whichdroplets of ink are ejected through a fine nozzle onto a substratewithout bringing the nozzle into contact with the substrate.

There are many demanding performance requirements for dyes and inks usedin IJP. For example they desirably provide sharp, non-feathered imageshaving good water-fastness, light-fastness and optical density. The inksare often required to dry quickly when applied to a substrate to preventsmudging, but they should not form a crust over the tip of an ink jetnozzle because this will stop the printer from working. The inks shouldalso be stable to storage over time without decomposing or forming aprecipitate which could block the fine nozzle.

WO 01/48090 relates to metal chelate azo compounds which comprise anaphthol component and certain heterocyclic groups. WO 01/48090 does notdisclose such compounds further substituted by a triazole ring.

According to a first aspect of the present invention there is provided ametal chelate compound of the Formula (1) and salts thereof:

wherein:

-   one of A and B is OH and the other is an azotriazole group; and-   M is a metal or boron; and-   n is 0 to 4.

Preferred azotriazole groups are of the Formula (2a), (2b), (2c), (2d)or (2e):

wherein:

-   Z is H, —OH, —Br, —Cl, —F, —CN, —NO₂, —PO₃H₂, —SO₃H, —CO₂H,    optionally substituted phosphoramide, optionally substituted alkyl,    optionally substituted alkenyl, optionally substituted alkynyl,    optionally substituted aryl, optionally substituted aralkyl, —SR¹,    —SO₂R¹, —SO₂NR²R³, —SOR¹, —OR¹, —C(O)R¹, —C(O)OR¹, —C(O)NR²R³,    —NR²R³, —NHCOR¹; and-   Y is CF₃ or any one of the groups defined for Z; and    wherein:-   R¹, R² and R³ are each independently H, optionally substituted    alkyl, optionally substituted alkenyl, optionally substituted    alkynyl, optionally substituted aryl or optionally substituted    aralkyl; or-   R² and R³ together with the nitrogen to which they are attached form    an optionally substituted 5- or 6- membered ring.

When Y or Z is optionally substituted phosphoramide the phosphoramide ispreferably substituted by optionally substituted alkyl, optionallysubstituted aryl or optionally substituted aralkyl. Preferredsubstituents include for example methyl, ethyl, n-propyl, iso-propyl,hydroxyethyl, optionally substituted phenyl or optionally substitutedbenzyl.

When Y or Z is optionally substituted alkyl, the alkyl group ispreferably optionally substituted C₁₋₄-alkyl, more preferably C₁₋₄-alkyloptionally substituted by halo, hydroxy, carboxy, sulpho or cyano.Examples include methyl, ethyl, n-propyl, iso-propyl, trifluoromethyl,hydroxyethyl, cyanoethyl, sulphopropyl and carboxyethyl. However, when Yor Z is optionally substituted alkyl it is especially preferred that thealkyl group is methyl, ethyl or trifluoromethyl.

When Y or Z is optionally substituted alkenyl, Y or Z is preferablyoptionally substituted C₂-C₄ alkenyl.

When Y or Z is optionally substituted alkynyl, Y or Z is preferablyoptionally substituted C₂-C₆ alkynyl.

When Y or Z is optionally substituted aryl the aryl group is preferablyoptionally substituted phenyl, optionally substituted naphthyl oroptionally substituted heteroaryl. It is especially preferred that whenY is optionally substituted aryl it is optionally substituted phenyl oroptionally substituted heteroaryl.

Preferred optional substituents on Y when Y is optionally substitutedaryl include sulpho, carboxy, nitro, cyano, halo (preferably chloro),alkoxy (preferably C₁₋₆-alkoxy), alkyl ((preferably C₁₋₆-alkyl)optionally substituted by halogen (preferably fluoro), hydroxy, carboxy,phosphoric acid and sulpho. Especially preferred optional substituentson Y when Y is optionally substituted aryl are selected from C₁₋₄-alkyl,carboxy, phosphoric acid and sulpho. However, it is most preferred thatwhen Y is optionally substituted aryl that the aryl group is substitutedby carboxy.

Preferred optional substituents on Z when Z is optionally substitutedaryl include sulpho, carboxy, nitro, cyano, halo (preferably chloro),alkoxy (preferably C₁₋₆-alkoxy), alkyl (preferably C₁₋₆-alkyl)optionally substituted by halogen (preferably fluoro), hydroxy, carboxy,phosphoric acid and sulpho. Especially preferred optional substituentson Z as optionally substituted aryl are selected from carboxy or halogen(preferably chloro).

When Y or Z is optionally substituted aralkyl the aralkyl group ispreferably optionally substituted benzyl.

However, Y in Formulae (2a), (2b), (2c), (2d) or (2e) is most preferablyH, thiol, carboxy, halo (preferably chloro), alkyl ((preferablyC₁₋₆-alkyl) optionally substituted by hydroxy, carboxy, halo (preferablyfluoro) or sulpho. It is especially preferred that Y in Formulae (2a) to(2e) is H, C₁₋₄-alkyl or carboxy or sulpho. However, it is mostespecially preferred that Y is H or CO₂H.

Z in Formulae (2a) to (2e) is preferably H, ethylester or alkyl(preferably C₁₋₄-alkyl) optionally substituted by hydroxy, carboxy, halo(preferably fluoro) or sulpho. It is especially preferred that Z inFormulae (2a) to (2e) is H or C₁₋₄-alkyl. However, it is most especiallypreferred that Z is H.

R¹, R² and R³ are preferably each independently H, optionallysubstituted C₁₋₄-alkyl or optionally substituted aryl, more preferablyH, C₁₋₄-alkyl optionally substituted by hydroxy, carboxy, sulpho orcyano or phenyl optionally substituted by hydroxy, carboxy, sulpho,nitro, trifluoromethyl or cyano. Examples of groups represented by R¹,R² and R³ include methyl, ethyl, n-propyl, iso-propyl, hydroxyethyl,cyanoethyl, sulphopropyl, carboxyethyl or carboxyphenyl. It isespecially preferred however that R¹, R² and R³ are H, optionallysubstituted C₁₋₄-alkyl for example, trifluoromethyl, hydroxyethyl orcyanoethyl, or optionally substituted aryl for example phenyl optionallysubstituted by carboxy; or R² and R³ together with the nitrogen to whichthey are attached form a 5- or 6- membered ring (preferably morpholine,piperidine or piperazine).

M preferably comprises boron or one or more of the following metals:nickel, chromium, cobalt, copper, zinc, iron or manganese. The metal M,is preferably able to co-ordinate to the portion of the compound ofFormula (1) within square brackets in the ratio 1:1, 2:1, 2:2, 2:3respectively. However, it is particularly preferred that M is nickel. Itis also preferred that M is able to co-ordinate to the portion of thecompound of Formula (1) within square brackets in the ratio 1:1 and 2:1.

It is preferable that n is 0, 1, 2 or 3 more preferably 1, 2 or 3,especially 1 or 2.

It is especially preferred that the compound of Formula (1) is a metalchelate compound of the Formula (3) or (4):

wherein D is an azotriazole group, preferably of Formula (2a), (2b),(2c), (2d) or (2e) as hereinbefore defined; n is 1 or 2; and M isnickel.

When the metal chelate compound is of Formula (3), it is preferred thatthere is one sulphonic acid group at the 4-position on the naphthyleneand one sulphonic acid group at the 8-position on the naphthylene ring,relative to D being at the 2-position on the naphthylene ring.

When the metal chelate compound is of Formula (4), it is preferred thatthere is one sulphonic acid group at the 3-position on the naphthylenering and one sulphonic acid group at the 7-position on the naphthylenering, relative to D being at the 1-position.

In view of the foregoing preferences the compound of Formula (1) ispreferably a metal chelate compound of the Formula (5) or (6) or a saltthereof:

wherein:

-   -   D is a group of Formula (2a), (2b), (2c), (2d) or (2e) as        hereinbefore defined and preferred, M is a metal, more        preferably nickel.

When D is a group of Formula (2a), (2b), (2c), (2d) or (2e), Y ispreferably H or CO₂H and Z is preferably H.

It is especially preferred that the compounds of Formula (1) are magentain colour.

The compounds of Formula (1) provide prints which exhibit a highlight-fastness and good optical density when incorporated into inks forink jet printing. The compounds of Formula (1) are also highly solublewhich improves operability and reduces crusting and nozzle blockage wheninks containing the compounds are used in an ink jet printer.

Compounds of Formula (1) are preferably free from fibre reactive groups.The term fibre reactive group is well known in the art and is describedfor example in EP 0356014 A1. Fibre reactive groups are capable, undersuitable conditions, of reacting with the hydroxyl groups present incellulosic fibres or with the amino groups present in natural fibres toform a covalent linkage between the fibre and the dye. As examples offibre reactive groups excluded from the compounds of Formula (1) theremay be mentioned aliphatic sulphonyl groups which contain a sulphateester group in the beta-position to the sulphur atom, e.g.beta-sulphato-ethylsulphonyl groups, alpha, beta-unsaturated acylradicals of aliphatic carboxylic acids, for example acrylic acid,alpha-chloro-acrylic acid, alpha-bromoacrylic acid, propiolic acid,maleic acid and mono- and dichloro maleic; also the acyl radicals ofacids which contain a substituent which reacts with cellulose in thepresence of an alkali, e.g. the radical of a halogenated aliphatic acidsuch as chloroacetic acid, beta-chloro and beta-bromopropionic acids andalpha, beta-dichloro- and dibromopropionic acids or radicals ofvinylsulphonyl- or beta-chloroethylsulphonyl- orbeta-sulphatoethyl-sulphonyl-endo- methylene cyclohexane carboxylicacids. Other examples of cellulose reactive groups aretetrafluorocyclobutyl carbonyl, trifluoro-cyclobutenyl carbonyl,tetrafluorocyclobutylethenyl carbonyl, trifluoro-cyclobutenylethenylcarbonyl; activated halogenated 1,3-dicyanobenzene radicals; andheterocyclic radicals which contain 1, 2 or 3 nitrogen atoms in theheterocyclic ring and at least one cellulose reactive substituent on acarbon atom of the ring.

The compounds of Formula (1) may be in the free acid or salt form.Preferred salts are water-soluble, for example alkali metal salts,especially lithium, sodium, potassium, ammonium, substituted ammoniumand mixed salts thereof. Preferred alkali metal salts are those withsodium, lithium, ammonium and substituted alkyl ammonium salts.

Preferred ammonium and substituted alkyl ammonium salts have cations ofthe formula ⁺NV₄ wherein each V independently is H or optionallysubstituted alkyl, or two groups represented by V are H or optionallysubstituted alkyl and the remaining two groups represented by V,together with the N atom to which they are attached, form a 5- or 6-membered ring (preferably a morpholinyl, pyridinyl or piperidinyl ring).

Preferably each V independently is H or C₁₋₄-alkyl, more preferably H,—CH₃ or CH₃CH₂—, especially H.

Examples of cations include ⁺NH₄, morpholinium, piperidinium,pyridinium, (CH₃)₃N⁺H, (CH₃)₂N⁺H₂, H₂N⁺(CH₃)(CH₂CH₃), CH₃N⁺H₃,CH₃CH₂N⁺H₃, H₂N⁺(CH₂CH₃)₂, CH₃CH₂CH₂N⁺H₃, (CH₃)₂CHN⁺H₃, N⁺(CH₃)₄,N⁺(CH₂CH₃)₄, N-methyl pyridinium, N,N-dimethyl piperidinium andN,N-dimethyl morpholinium.

It is especially preferred that the compound is in the form of a sodium,lithium, potassium, ammonium or substituted ammonium salt.

Preferably the metal chelate compound is not a copper or nickel chelateof any of Ligands a to e or any salt thereof:

Preferably the metal chelate compound is not a chrome chelate of Ligandf or any salt thereof:

Preferably the metal chelate compound is not a cobalt chelate of Ligandsg or h or any salt thereof:

Preferably the metal chelate compound is not a chrome chelate of Ligandi or j or any salt thereof:

Preferably the metal chelate compound is not a metal chelate of Ligandk, l or m or any salt thereof:

Preferably the metal chelate compound is not a metal chelate of any ofthe above Ligands f to m inclusive, more preferably a to m inclusive, orany salt thereof.

Preferably the compounds of the invention have a chroma of at least 50when printed on plain paper.

The compounds of Formula (1) may be converted into a salt using knowntechniques. For example, an alkali metal salt of a compound may beconverted into a salt with ammonia or an amine by dissolving an alkalimetal salt of the dye in water and passing the solution through a columnof a suitably modified ion exchange resin.

The compounds of Formula (1) may be prepared using conventionaltechniques for the preparation of metal chelate compounds. For example,a suitable method comprises adding together a metal salt and a solutionof a compound of Formula (7):

wherein A, B and n are as hereinbefore defined in relation to Formula(1).

The product of the above process may be converted to a salt byconventional techniques as hereinbefore described. Alternatively, theproduct may be isolated in its free acid form by acidifying the reactionmixture, preferably using a mineral acid, for example hydrochloric acidand when the product precipitates as a solid it may be separated fromthe mixture by filtration. Unwanted anions may be and preferably areremoved from the product of the above process by dialysis, osmosis,ultra filtration or a combination thereof. Alternatively, the productsolution is subjected to the above purification directly withoutisolation of the product.

The compounds of Formula (7) may be prepared by, for example,diazotising a compound of the formula A¹-NH₂ to give a diazonium saltand coupling the resultant diazonium salt with a compound of the Formula(7a):

wherein A¹ is a triazole group, one of B and L is OH and the other is Hand n is as hereinbefore defined in relation to Formula (1).

The diazotisation is preferably performed at a temperature below 6° C.,more preferably at a temperature in the range −10° C. to 5° C.Preferably the diazotisation is performed in water, preferably at a pHbelow 7. Dilute mineral acid, e.g. HCl or H₂SO₄, are often used toachieve the desired acidic conditions.

The present invention also covers mixtures comprising two or morecompounds of the Formula (1) or salts thereof. Furthermore, thecompounds of Formula (1) may be mixed with commercially available dyes,especially those listed in the International Colour Index, to adjust theshade or other properties as desired.

According to a second aspect of the present invention there is provideda composition comprising:

-   -   (a) one or more compound according to the first aspect of the        present invention; and    -   (b) one or more water-soluble dye other than a compound        according to the first aspect of the invention.

The water-soluble dye is preferably a water-soluble magenta dye, forexample a xanthene dye, an azo or bis azo dye, more preferably ananionic azo or bis azo dye and especially an azo or bis azo dye whichcontains one or more groups selected from sulphonate, carboxylate andthiocarboxylate groups.

Preferred water-soluble magenta dyes include C.I. Acid Red 50, 52, 87,91, 92, 95, 249 and 289; C.I. Direct Violet 106 and 107; compounds 100to 107, 200 and 201 described on pages 8 and 9 of WO96/24636; compounds1 to 24 shown described on columns. 4 to 10 in U.S. Pat. No. 5,542,970;compounds 1 to 55 described on pages 7 to 17 of EP-A-682 088; compounds1 to 14 shown in Example 1 to 6 of EP-A-194,885; compounds 1 to 24described on pages 8 to 13 of EP-A-717 089; the compounds described inexamples 1 to 16 in columns. 5 to 11 of U.S. Pat. No. 5,262,527; and thedyes described in Examples 1 to 21 in WO 94/16021.

Especially preferred water-soluble magenta dyes for use in thecomposition according to the second aspect of the invention include C.I.Acid Red 52, C.I. Acid Red 289 or a dye of the Formula (8), (9) and (10)and salts thereof:

The dye of Formula (8) may be prepared using the method described inExample 1 of EP 0 559 310. The dye of the Formula (9) may be preparedusing the method described in Example 3 of PCT publication number WO94/16021. The dye of Formula (10) may be prepared using the methoddescribed in Example 1 of WO 96/24636.

The composition according to the second aspect of the present inventionpreferably comprises:

-   (a) from 1 to 99, more preferably from 3 to 70 and especially from 5    to 50 parts in total of the compound(s) according to the first    aspect of the invention; and-   (b) from 99 to 1, more preferably from 30 to 97 parts and especially    95 to 50 parts in total of the water-soluble magenta dye(s);    wherein the parts are by weight and the sum of the parts    (a)+(b)=100.

The composition may contain a single dye of Formula (1) or a mixturethereof. Similarly, the composition may contain a single water-solublemagenta dye or a mixture of two or more water-soluble magenta dyes.

The compounds and compositions according to the first and second aspectsof the present invention may be, and preferably are, purified to removeundesirable impurities before they are incorporated into inks for inkjet printing. Conventional techniques may be employed for purification,for example ultrafiltration, reverse osmosis and/or dialysis.

According to a third aspect of the present invention there is providedan ink comprising:

-   (a) a compound according to the first aspect of the present    invention, or a composition according to the second aspect of the    invention; and-   (b) a liquid medium.

Preferably component (a) of the ink is or comprises one of the preferredcompounds or compositions as hereinbefore described in relation to thefirst or second aspect of the invention.

The liquid medium preferably comprises:

-   -   (i) water;    -   (ii) a mixture of water and an organic solvent; or    -   (iii) an organic solvent free from water.

The number of parts by weight of component (a) of the ink is preferablyfrom 0.01 to 30, more preferably 0.1 to 20, especially from 0.5 to 15,and more especially from 1 to 5 parts. The number of parts by weight ofcomponent (b) is preferably from 99.99 to 70, more preferably from 99.9to 80, especially from 99.5 to 85, and more especially from 99 to 95parts. The number of parts (a)+(b) is 100 and all parts mentioned hereare by weight.

Preferably component (a) is completely dissolved in component (b).Preferably component (a) has a solubility in component (b) at 20° C. ofat least 10%. This allows the preparation of concentrates which may beused to prepare more dilute inks and reduces the chance of thecompound(s) of component (a) of the ink precipitating if evaporation ofthe liquid medium occurs during storage.

When the liquid medium comprises a mixture of water and an organicsolvent, the weight ratio of water to organic solvent is preferably from99:1 to 1:99, more preferably from 99:1 to 50:50 and especially from95:5 to 80:20.

It is preferred that the organic solvent present in the mixture of waterand organic solvent is a water-miscible organic solvent or a mixture ofsuch solvents. Preferred water-miscible organic solvents includeC₁₋₆-alkanols, preferably methanol, ethanol, n-propanol, isopropanol,n-butanol, sec-butanol, tert-butanol, n-pentanol, cyclopentanol andcyclohexanol; linear amides, preferably dimethylformamide ordimethylacetamide; ketones and ketone-alcohols, preferably acetone,methyl ether ketone, cyclohexanone and diacetone alcohol; water-miscibleethers, preferably tetrahydrofuran and dioxane; diols, preferably diolshaving from 2 to 12 carbon atoms, for example pentane-1,5-diol, ethyleneglycol, propylene glycol, butylene glycol, pentylene glycol, hexyleneglycol and thiodiglycol and oligo- and poly-alkyleneglycols, preferablydiethylene glycol, triethylene glycol, polyethylene glycol andpolypropylene glycol; triols, preferably glycerol and 1,2,6-hexanetriol;mono-C₁₋₄-alkyl ethers of diols, preferably mono-C₁₋₄-alkyl ethers ofdiols having 2 to 12 carbon atoms, especially 2-methoxyethanol,2-(2-methoxyethoxy)ethanol, 2-(2-ethoxyethoxy)-ethanol,2-[2-(2-methoxyethoxy)ethoxy] ethanol, 2-[2-(2-ethoxyethoxy)-ethoxy]-ethanol and ethyleneglycol monoallylether; cyclic amides,preferably 2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone,caprolactam and 1,3-dimethylimidazolidone; cydic esters, preferablycaprolactone; sulphoxides, preferably dimethyl sulphoxide andsulpholane. Preferably the liquid medium comprises water and 2 or more,especially from 2 to 8, water-miscible organic solvents.

Especially preferred water-soluble organic solvents are cyclic amides,especially 2-pyrrolidone, N-methyl-pyrrolidone and N-ethyl-pyrrolidone;diols, especially 1,5-pentane diol, ethyleneglycol, thiodiglycol,diethyleneglycol and triethyleneglycol; and mono- C₁₋₄-alkyl andC₁₋₄-alkyl ethers of diols, more preferably mono- C₁₋₄-alkyl ethers ofdiols having 2 to 12 carbon atoms, especially2-methoxy-2-ethoxy-2-ethoxyethanol.

A preferred liquid medium comprises:

-   (a) from 75 to 95 parts water; and-   (b) from 25 to 5 parts in total of one or more solvents selected    from diethylene glycol, 2-pyrrolidone, thiodiglycol,    N-methylpyrrolidone, cyclohexanol, caprolactone, caprolactam and    pentane-1,5-diol;    wherein the parts are by weight and the sum of the parts (a) and    (b)=100.

Another preferred liquid medium comprises:

-   (a) from 60 to 80 parts water;-   (b) from 2 to 20 parts diethylene glycol; and-   (c) from 0.5 to 20 parts in total of one or more solvents selected    from 2-pyrrolidone, N-methylpyrrolidone, cyclohexanol, caprolactone,    caprolactam, pentane-1,5-diol and thiodiglycol;    wherein the parts are by weight and the sum of the parts (a), (b)    and (c)=100.

Examples of further suitable ink media comprising a mixture of water andone or more organic solvents are described in U.S. Pat. No. 4,963,189,U.S. Pat. No. 4,703,113, U.S. Pat. No. 4,626,284 and EP 4,251,50A.

When the liquid medium comprises an organic solvent free from water,(i.e. less than 1% water by weight) the solvent preferably has a boilingpoint of from 300 to 200° C., more preferably of from 400 to 150° C.,especially from 50 to 125° C. The organic solvent may bewater-immiscible, water-miscible or a mixture of such solvents.Preferred water-miscible organic solvents are any of the hereinbeforedescribed water-miscible organic solvents and mixtures thereof.Preferred water-immiscible solvents include, for example, aliphatichydrocarbons; esters, preferably ethyl acetate; chlorinatedhydrocarbons, preferably CH₂Cl₂; and ethers, preferably diethyl ether;and mixtures thereof.

When the liquid medium comprises a water-immiscible organic solvent,preferably a polar solvent is included because this enhances solubilityof the dye in the liquid medium. Examples of polar solvents includeC₁₋₄-alcohols. In view of the foregoing preferences it is especiallypreferred that where the liquid medium is an organic solvent free fromwater it comprises a ketone (especially methyl ethyl ketone) and/or analcohol (especially a C₁₋₄-alkanol, such as ethanol or propanol).

The organic solvent free from water may be a single organic solvent or amixture of two or more organic solvents. It is preferred that when themedium is an organic solvent free from water it is a mixture of 2 to 5different organic solvents. This allows a medium to be selected whichgives good control over the drying characteristics and storage stabilityof the ink.

Ink media comprising an organic solvent free from water are particularlyuseful where fast drying times are required and particularly whenprinting onto hydrophobic and non-absorbent substrates, for exampleplastics, metal and glass.

An especially preferred ink comprises:

-   (a) from 1 to 10 parts in total of a compound or composition    according to the first or second aspect of the invention;-   (b) from 2 to 60, more preferably 5 to 40 parts of water-soluble    organic solvent; and-   (c) from 30 to 97, more preferably 40 to 85 parts water;    wherein all parts are by weight and the sum of the parts (a) +(b)    +(c)=100.

When the liquid medium in the ink comprises a mixture of water and anorganic solvent; or an organic solvent free from water, component (a) ofthe ink may comprise a compound of the Formula (1), or salt thereof, ashereinbefore defined in relation to the first aspect of the invention.

Preferred low melting solid media have a melting point in the range from60° C. to 125° C. Suitable low melting point solids include long chainfatty acids or alcohols, preferably those with C₁₈₋₂₄ chains, andsulphonamides. A dye of Formula (1) may be dissolved in the low meltingpoint solid or may be finely dispersed in it.

The inks according to the present invention may also contain additionalcomponents conventionally used in ink jet printing inks, for exampleviscosity and surface tension modifiers, corrosion inhibitors, biocides,kogation reducing additives, anti-cockle agents to reduce paper curlingand surfactants which may be ionic or non-ionic.

The pH of the ink is preferably from 4 to 11, more preferably from 7 to10.

The viscosity of the ink at 25° C. is preferably less than 50 cP, morepreferably less than 20 cP and especially less than 5 cP.

When the inks according to the invention are used as ink jet printinginks, the ink preferably has a concentration of less than 500 parts permillion, more preferably less than 100 parts per million of halide ions.It is especially preferred that the ink has less than 100, morepreferably less than 50 parts per million of divalent and trivalentmetals, wherein parts refer to parts by weight relative to the totalweight of the ink. We have found that purifying the inks to reduce theconcentration of these undesirable ions reduces nozzle blockage in inkjet printing heads, particularly in thermal ink jet printers.

A fourth aspect of the present invention provides a process for printingan image on a substrate comprising applying thereto by means of an inkjet printer an ink containing a compound according to the first aspectof the invention or a composition according to the second aspect of theinvention.

The ink used in this process is preferably as defined in the thirdaspect of the present invention.

The ink jet printer preferably applies the ink to the substrate in theform of droplets which are ejected through a small orifice onto thesubstrate. Preferred ink jet printers are piezoelectric ink jet printersand thermal ink jet printers. In thermal ink jet printers, programmedpulses of heat are applied to the ink in a reservoir by means of aresistor adjacent to the orifice, thereby causing the ink to be ejectedin the form of small droplets directed towards the substrate duringrelative movement between the substrate and the orifice. Inpiezoelectric ink jet printers the oscillation of a small crystal causesejection of the ink from the orifice.

The substrate is preferably paper, plastic, a textile, metal or glass,more preferably paper, an overhead projector slide or a textilematerial, especially paper.

Preferred papers are plain or treated papers which may have an acid,alkaline or neutral character. Examples of commercially available papersinclude, HP Premium Coated Paper, HP Photopaper (all available fromHewlett Packard Inc.), Stylus Pro 720 dpi Coated Paper, Epson PhotoQuality Glossy Film, Epson Photo Quality Glossy Paper (available fromSeiko Epson Corp.), Canon HR 101 High Resolution Paper, Canon GP 201Glossy Paper, Canon HG 101 High Gloss Film (all available from CanonInc.), Wiggins Conqueror paper (available from Wiggins Teape Ltd), XeroxAcid Paper and Xerox Alkaline paper, Xerox Acid Paper (available fromXerox).

A fifth aspect of the present invention provides a substrate, preferablya paper, an overhead projector slide or a textile material, printed withan ink according to the third aspect of the present invention or bymeans of the process according to the fourth aspect of the presentinvention.

According to a sixth aspect of the present invention there is providedan ink jet printer cartridge comprising a chamber and ink, wherein theink is present in the chamber and the ink contains a compound or acomposition according to the first or second aspect of the presentinvention. Preferably the ink is as defined in the third aspect of thepresent invention.

According to a seventh aspect of the present invention there is providedan ink jet printer containing an ink jet printer cartridge, wherein theink jet printer cartridge is as defined in the sixth aspect of thepresent invention.

The invention is further illustrated by the following Examples in whichall parts and percentages are by weight unless otherwise stated.

EXAMPLE 1 Preparation of Compound (1) Wherein M is Nickel

Stage (a): Preparation of 3-hydroxynaphthalene-2,6-disulfonic Acid

7-Hydroxynaphthalene-2-sulfonic acid (250 g, 1.16 mol) was added inportions to a mixture of concentrated H₂SO₄ (950 g) and water (50 g).The mixture was stirred at 110-120° C. for 3 hours, cooled to roomtemperature, added to a mixture of ice and water (5000 ml) and theproduct precipitated by the addition of sodium chloride. The resultantslurry was warmed to 90° C. to dissolve the product, stirred for 1 hourat this temperature and then allowed to cool. The product was filteredoff and the damp product dissolved in water (3000 ml) at pH 10 by theaddition of concentrated sodium hydroxide solution. The solution wasthen filtered to remove a small amount of insoluble material. The pH ofthe filtrate was lowered to 7 with concentrated HCl and the productprecipitated by the addition sodium chloride. The product was filteredoff and dried in a vacuum oven to give 117 g of a cream solid (68%yield).Stage (b):

3-amino-1,2,4-triazole-5-carboxylic acid hydrate (3.84 g, 0.03 mol) wassuspended in water (180 ml) and dissolved by the addition of 2M NaOH topH 8. Sodium nitrite (2.27 g, 0.033 mol) was added and the solutionstirred until the sodium nitrite had dissolved.

The mixture was then added dropwise to a cooled mix of ice-water (150 g)and concentrated HCl (10 ml) at 0-5° C., the mixture was stirred for 30minutes at 0-5° C. and then excess nitrous acid was removed by addingsulphamic acid. The diazo suspension was added slowly to a solution of3-hydroxynaphthalene-2,6-disulfonic acid (13.4 g, 0.03 mol) in water(300 ml) at pH 7-8 (2N NaOH) and cooled below 5° C. The reaction mixturewas then stirred at 0-5° C. for one further hour, the product wasprecipitated by acidification to pH 4 with 2N HCl and collected byfiltration. The product was washed with 15% brine solution and thendried in a vacuum desiccator to give 20 g of an orange solid (60%yield).

Stage (c): Preparation of Compound (1)

A solution of nickel acetate tetrahydrate (2.5 g, 0.01 mol) in water (20ml) was added dropwise to the product from stage (b) (7.43 g, 0.01 mol)dissolved in water (100 ml) at pH 7-8 (2N NaOH). The reaction mixturewas stirred for 2 hours at 20° C., dialysed using SpectraPor membranetubing (molecular weight cut off 3500) to low conductivity (<100 μs).Compound (1) was obtained by evaporation under reduced pressure toafford a dark solid (5 g). Analysis by mass spectrometry found m/z 499(M-H)⁻. Requires M⁺=500.

EXAMPLES 2 to 5

Compounds (2) to (5) of the Formula (11) were prepared using ananalogous process to that described in Example 1 except that in stage(c) a metal salt as shown in Table 1 was used in place of nickelacetate.

TABLE 1 Example Compound Metal salt M Mass spectra analysis 2 (2) Copperacetate Cu m/z 504 (M − H)⁻ 3 (3) Chromium acetate Cr m/z 934 (M − H)⁻ 4(4) Zinc acetate Zn m/z 947 (M − H)⁻ 5 (5) Cobalt acetate Co m/z 941 (M− H)⁻

EXAMPLE 6 to 8

Compounds (6) to (8) of the Formula (12) described in Table 2 wereprepared using an analogous process to that described in Example 1except that in stage (b) in place of 3-amino-1,2,4-triazole-5-carboxylicacid there was used the triazole compound shown in Table 2. The name ofthe resultant Compound is shown in the third column of Table 2. M isnickel.

TABLE 2 Example Triazole Y Compound name 6

CF₃ Nickel chelate of [3-hydroxy-4-(5-trifluomethyl-1H-[1,2,4]triazole-3-ylazo)-naphthalene-2,7- disulfonic acid (“Compound(6)”). Analysis by mass spectrometry found m/z 989 (M − H)⁻. 7

H Nickel chelate of [3-hydroxy-4-(1H-[1,2,4]triazole-3-ylazo)-naphthalene-2,7- disulfonic acid. (“Compound(7)”). Analysis by mass spectrometry found m/z 853 (M − H)⁻. 8

C₆H₅ Nickel chelate of [3-hydroxy-4-(5-phenyl-1H-[1,2,4]triazole-3-ylazo)-naphthalene-2,7- disulfonic acid. (“Compound(8)”). Analysis by mass spectrometry found m/z 1007 (M − H)⁻.

EXAMPLE 9

Compound (9) of the Formula (13) described in Table 3 was prepared usingan analogous process to that described in Example 1 except that in stage(b) in place of 3-hydroxynaphthalene-2,6-disulfonic acid there was used2-hydroxynaphthalene-3,6-disulfonic acid.

Compounds (10) and (11) of the Formula (13) described in Table 3 wereprepared using an analogous process to that described in Example 1except that in stage (b) in place of 3-hydroxynaphthalene-2,6-disulfonicacid there was used 2-hydroxynaphthalene-3,6-disulfonic acid and inplace of 3-amino-1,2,4-triazole-5-carboxylic acid there was used theamino triazole compound shown in Table 3.

TABLE 3 Example Triazole Y Dye name 9

CO₂H Nickel chelate of [5-(2-hydroxy-3,6-disulfo-naphthalen-1-ylazo)-2H-[1,2,4]triazole-3- carboxylic acid]. (“Compound(9)”). Analysis by mass spectrometry found mlz 941 (M − H)⁻. 10

SH Nickel chelate of [3-hydroxy-4-(5-mercapto-1H-[1,2,4]triazole-3-ylazo)-naphthalene-2,7-disulfonic acid]. (“Compound(10)”). 11

SCH₃ Nickel chelate of [3-hydroxy-4-(5-methylsulfanyl-1H-[1,2,4]triazole-3-ylazo)-naphthalene-2,7- disulfonic acid].(“Compound (11)”). Analysis by mass spectrometry found m/z 501 (M − H)⁻.

EXAMPLE 12

Compound (12) Wherein M is Copper:

Compound (12) was prepared using an analogous process to that describedin Example 1 except that in stage (b)2-hydroxynaphthalene-3,6-disulfonic acid was used in place of3-hydroxynaphthalene-2,6-disulfonic acid and in stage (c) copper acetatewas used in place of nickel acetate.

EXAMPLE 13

Preparation of Compound (13) Wherein M is Nickel:

Stage (a):

The product of Example 1 stage (a) (5g), (0.016 mol) was added inportions during the course of 30 minutes to 27% oleum (10 ml) withstirring at room temperature. A second portion of 27% oleum (10 ml) wasadded and the reaction mixture stirred overnight at room temperature.The reaction mixture was then stirred for 3.5 hours at 120° C., cooledand the product collected by filtration using a sintered funnel andwashed with concentrated H₂SO₄ (5 ml). The crude product was dissolvedin water (20 ml) and precipitated by the addition of sodium chloride.The solid was collected by filtration and dried to give a pale pinksolid.Stage(b): Preparation of Compound (13) Wherein M is Nickel:

The Compound (13) was prepared using an analogous process to thatdescribed in Example 1 except that in stage (b)2-hydroxy-naphthalene-1,3,5,7-tetrasulphonic acid was used in place of3-hydroxynaphthalene-2, 6-disulfonic acid. Analysis by mass spectrometryfound m/z 579 (M-H)⁻.

EXAMPLE 14

Preparation of Compound (14) Wherein M is Nickel:

Compound (14) was prepared using an analogous process to that describedin Example 1 except that in stage (b)7-hydroxynaphthalene-1,3,6-trisulfonic acid was used in place of3-hydroxynaphthalene-2,6-disulfonic acid. Analysis by mass spectrometryfound m/z 1101 (M-H)⁻.

EXAMPLE 15

Preparation of Compound (15) Wherein M is Nickel:

Stage (a): Preparation of5-(1-hydroxy-4-sulfo-naphthalen-2-ylazo)-2H-[1,2,4]triazole

3-amino-1,2,4-triazole-5-carboxylic acid hydrate (1.28 g, 0.01 mol) wassuspended in water (50 ml) and dissolved by the addition of 2M NaOH topH 8. Sodium nitrite (0.76 g, 0.11 mol) was added and the solutionstirred until the sodium nitrite had dissolved.

The mixture was then added dropwise to a cooled mix of ice-water (30 g)and concentrated HCl (3.0 ml) at 0-5° C., the mixture was stirred for 30minutes at 0-5° C. and then excess nitrous acid was removed by addingsulphamic acid. The diazo suspension was added slowly to a solution of4-hydroxy-naphthalene-1-sulfonic acid sodium salt (2.46 g, 0.01 mol) inwater (100 ml) at pH 10-10.5 (2N NaOH) and cooled below 5° C. Thereaction mixture was then stirred at 0-5° C. for one further hour, theproduct was precipitated by acidification to pH 4 with 2N HCl andcollected by filtration. The product was washed with water and thendried in a vacuum desiccator to give 2.9 g of an orange solid.

Stage (b): Preparation of Compound (15):

A solution of nickel acetate tetrahydrate (1.39, 0.005 mol) in water (10ml) was added dropwise to the product from stage (a) (1.9 g, 0.005 mol)dissolved in water (100 ml) at pH 7-8 (2N NaOH). The reaction mixturewas stirred for 2 hours at 20° C., dialysed using SpectraPor membranetubing (molecular weight cut off 3500) to low conductivity (<100 μs).The product was obtained by evaporation under reduced pressure to afforda dark solid (1.7 g). Analysis by mass spectrometry found m/z 781(M-H)⁻.

EXAMPLES 16 & 17

Compounds (16) and (17) described in Table 4 of the Formula (14) wereprepared using an analogous process to that described in Example 15except that in stage (b) the metal salt (M) shown in Table 4 was used inplace of nickel acetate.

TABLE 4 Mass spectra Example Compound Metal salt M analysis 16 (16)Cobalt acetate Co m/z 781 (M − H)⁻ 17 (17) Chromium acetate Cr m/z 827(M − H)⁻

EXAMPLE 18

Preparation of Compound (18) Wherein M is Nickel:

Compound (18) was prepared using an analogous process to that describedin Example 15 except that in stage (a)3-amino-5-methylthio-1,2,4-triazole was used in place of3-amino-1,2,4-triazole-5-carboxylic acid. Analysis by mass spectrometryfound m/z 785 (M-H)⁻.

EXAMPLE 19

Preparation of Compound (19) Wherein M is Nickel:

Stage (a):

1,8-Naphthosultone (25.0 g, 0.119 mol) was added in portions toconcentrated sulphuric acid (75 ml), the reaction mixture was thenstirred for 2 hours at 80° C. and then added to a mixture of ice (70 g)and water (20 ml). Anhydrous sodium sulfate (46 g) was added in portionsto the reaction mixture at 30° C., the product was collected byfiltration and then dissolved in water (120 ml) at 50° C. The productwas precipitated by the addition of sodium chloride (25% w/v), stirredat 40° C. for 1 hour and then collected by filtration. The solid wasdried in a vacuum oven to give 30 g of a pink solid (76%).Stage (b) - Preparation of 4-hydroxy-1,5-disulphonaphthalene:

The product from stage (a) (30 g) was dissolved in water (200 ml) at pH11 by the addition of 2N sodium hydroxide. The solution was stirred atroom temperature for 2 hrs to complete the hydrolysis and the solutionof the product used in the next stage without isolation.

Stage (c)

Compound (19) was prepared using an analogous process to that describedin Example 15 except that in the process of Example 15, stage (a),4-hydroxy-1,5-disulphonaphthalene acid was used in place of4-hydroxy-naphthalene-1-sulfonic acid. Analysis by mass spectrometryfound m/z 941 (M-H)⁻.

EXAMPLES 20 & 21

Compounds (20) and (21) described in Table 5 of the Formula (15) wereprepared using an analogous process to that described in Example 15except that in stage (a) 4-hydroxy-naphthalene-1,5-disulfonic acid wasused in place of 4-hydroxy-naphthalene-1-sulfonic acid and in place of3-amino-1,2,4-triazole-5-carboxylic acid the amino triazole compoundshown in Table 5 was used.

TABLE 5 Example Y Triazole Dye name 20 —CF₃

Nickel chelate of [4- hydroxy-3-(5-trifluoro- methyl-1H-[1,2,4]triazole-3-ylazo)-naphthalene-1,5- disulfonic acid]. (“Compound (20)”). Analysisby mass spectrometry found m/z 989 (M − H)⁻. 21 —H

Nickel chelate of [4- hydroxy-3-(1H-[1,2,4]triazol-3-ylazo)-naphthalene-1,5-disulfonic acid]. (“Compound (21)”). Analysis by massspectrometry found m/z 853 (M − H)⁻.

EXAMPLE 22

Preparation of Compound (22) Wherein M is Nickel:

Compound (22) was prepared using an analogous process to that describedin Example 15 except that in stage (a)8-hydroxy-naphthalene-1,3,6-trisulfonic acid was used in place of4-hydroxy-naphthalene-1-sulfonic acid. Analysis by mass spectrometryfound m/z 1157 (M-H)⁻.

EXAMPLE 23

Preparation of Compound (23) Wherein M is Nickel:

Compound (23) was prepared using an analogous process to that describedin Example 15 except that in stage (a)8-hydroxy-naphthalene-1,3,6-trisulfonic acid was used in place of4-hydroxy-naphthalene-1-sulfonic acid and 3-amino-1,2,4-triazole wasused in place of 3-amino-1,2,4-triazole-5-carboxylic acid. Analysis bymass spectrometry found m/z 534 (M-H)⁻.

Inks

The inks described in Tables I and II may be prepared wherein theCompound described in the first column is the Compound made in the aboveExamples of the same number. Numbers quoted in the second column onwardsrefer to the number of parts of the relevant ingredient and all partsare by weight. The inks may be applied to paper by thermal or piezo inkjet printing.

The following abbreviations are used in Table I and II:

-   PG=propylene glycol-   DEG=diethylene glycol-   NMP=N-methyl pyrollidone-   DMK=dimethylketone-   IPA=isopropanol-   MEOH=methanol-   2P=2-pyrollidone-   MIBK=methylisobutyl ketone-   P12=propane-1,2-diol-   BDL=butane-2,3-diol-   CET=cetyl ammonium bromide-   PHO=Na₂HPO₄ and-   TBT=tertiary butanol

TDG=thiodiglycol TABLE I Dye Na Compound Content Water PG DEG NMP DMKNaOH Stearate IPA MEOH 2P MIBK 1 2.0 80 5 6 4 5 2 3.0 90 5 5 0.2 3 10.085 3 3 3 5 1 4 2.1 91 8 1 5 3.1 86 5 0.2 4 5 6 1.1 81 9 0.5 0.5 9 7 2.560 4 15 3 3 6 10 5 4 8 5 65 20 10 9 2.4 75 5 4 5 6 5 10 4.1 80 3 5 2 100.3 11 3.2 65 5 4 6 5 4 6 5 12 5.1 96 4 13 10.8 90 5 5 14 10.0 80 2 6 25 1 4 15 1.8 80 5 15 16 2.6 84 11 5 17 3.3 80 2 10 2 6 18 12.0 90 7 0.33 19 5.4 69 2 20 2 1 3 3 20 6.0 91 4 5

TABLE II Dye Compound Content Water PG DEG NMP CET TBT TDG BDL PHO 2PPI2 21 3.0 80 15 0.2 5 22 9.0 90 5 1.2 5 23 1.5 85 5 5 0.15 5.0 0.2 42.5 90 6 4 0.12 5 3.1 82 4 8 0.3 6 1 0.9 85 10 5 0.2 7 8.0 90 5 5 0.3 84.0 70 10 4 1 4 11 9 2.2 75 4 10 3 2 6 10 10.0 91 6 3 1 9.0 76 9 7 3.00.95 5 12 5.0 78 5 11 6 13 5.4 86 7 7 20 2.1 70 5 5 5 0.1 0.2 0.1 5 0.15 15 2.0 90 10 1 2 88 10 2 5 78 5 12 5 1 8 70 2 8 15 5 1 10 80 8 12 1 1080 10

1. A metal chelate compound of the Formula (1) and salts thereof:

wherein: one of A and B is OH and the other is an azotriazole group; andM is a metal or boron; and n is
 3. 2. A compound according to claim 1wherein the azotriazole group is of the Formula (2a), (2b), (2c), (2d)or (2e):

wherein: Z is H, —OH, —Br, —Cl, —F, —CN, —NO₂, —PO₃H₂, —SO₃H, —CO₂H,optionally substituted phosphoramide, optionally substituted alkyl,optionally substituted alkenyl, optionally substituted alkynyl,optionally substituted aryl, optionally substituted aralkyl, —SR¹,—SO₂R¹, —SO₂NR²R³, —SOR¹, —OR¹, —C(O)R¹, —C(O)OR¹, —C(O)R²R³, —NR²R³,—NHCOR¹; and Y is —CF₃ or any one of the groups defined for Z; andwherein: R¹, R² and R³ are each independently H, optionally substitutedalkyl, optionally substituted alkenyl, optionally substituted alkynyl,optionally substituted aryl or optionally substituted aralkyl; or R² andR³ together with the nitrogen to which they are attached form anoptionally substituted 5- or 6- membered ring.
 3. A compound accordingto claim 1 or 2 wherein M is nickel.
 4. A compound according to claim 3wherein Y is CO₂H or H and Z is H.
 5. A compound according to claim 4wherein M is nickel.
 6. (canceled)
 7. (canceled)
 8. (canceled) 9.(canceled)
 10. (canceled)
 11. A compound according to claim 1 having anyone of the following formulae or a salt thereof, wherein M is nickel:


12. A composition comprising: (a) one or more compound according toclaim 1 or claim 11; and (b) one or more water-soluble dye other than acompound according to claim
 1. 13. An ink comprising: (a) a compoundaccording to claim 1; and (b) a liquid medium.
 14. An ink according toclaim 13, 19 or 20 wherein the liquid medium comprises a mixture ofwater and an organic solvent.
 15. A process for printing an image on asubstrate comprising applying thereto by means of an ink jet printer anink according to claim
 13. 16. A substrate printed by means of theprocess according to claim
 15. 17. An ink jet printer cartridgecomprising a chamber and ink, wherein the ink is present in the chamberand the ink is as defined in claim
 13. 18. An ink jet printer containingan ink jet printer cartridge, wherein the ink jet printer cartridge isas defined in claim
 17. 19. An ink comprising: (a) a compound accordingto claim 11; and (b) a liquid medium.
 20. An ink according to claim 19wherein the compound is Compound 13.